Method of managing patient temperature with a heat exchange catheter

ABSTRACT

A central venous catheter includes coolant supply and return lumens which communicate coolant to and from first and second heat exchange membranes arranged along the distal segment of the catheter. The coolant in the heat exchange membranes removes heat from the patient. Additional lumens are provided for conventional central venous catheter uses.

RELATED APPLICATION

[0001] Priority is claimed from co-pending U.S. patent application Ser.No. 09/253,109, filed Feb. 19, 1999.

FIELD OF THE INVENTION

[0002] The present invention relates generally to methods and apparatusfor cooling patients for therapeutic purposes, and more particularly tosystems for establishing central venous access while providing a meansfor cooling a patient.

BACKGROUND

[0003] It has been discovered that the medical outcome for a patientsuffering from severe brain trauma or from ischemia caused by stroke orheart attack is degraded if the patient's body temperature rises abovenormal (38° C.). It is further believed that the medical outcome formany such patients might be significantly improved if the patients wereto be cooled relatively quickly for a short period, e.g., 24-72 hours.Apart from the therapeutic benefits of hypothermia, the outcomes forbrain trauma or ischemia patients that develop fevers is worse than forpatients that do not develop fevers. Consequently, temperaturemanagement for such patients is important, even when hypothermia is notto be used to treat the patients. Moreover, prophylactic short-termhypothermia might help patients undergoing minimally invasive heartsurgery and aneurysm surgery.

[0004] The affected organ, in any case, is the brain. Accordingly,systems and methods have been disclosed that propose cooling bloodflowing to the brain through the carotid artery. An example of suchsystems and methods is disclosed in co-pending U.S. patent applicationSer. No. 09/063,984, filed Apr. 21, 1998, owned by the present assigneeand incorporated herein by reference. In the referenced application,various catheters are disclosed which can be advanced into a patient'scarotid artery and through which coolant can be pumped in a closedcircuit, to remove heat from the blood in the carotid artery and therebycool the brain. The referenced devices have the advantage over othermethods of cooling (e.g., wrapping patients in cold blankets) of beingcontrollable, relatively easy to use, and of being capable of rapidlycooling and maintaining blood temperature at a desired set point.

[0005] As recognized in co-pending U.S. patent application Ser. No.09/133,813, filed Aug. 13, 1998, owned by the present assignee andincorporated herein by reference, the above-mentioned advantages intreating brain trauma/ischemic patients by cooling can also be realizedby cooling the patient's entire body, ie., by inducing systemichypothermia. The advantage of systemic hypothermia is that, asrecognized by the present assignee, to induce systemic hypothermia acooling catheter or other cooling device need not be advanced into theblood supply of the brain, but rather can be easily and quickly placedinto the relatively large vena cava of the central venous system.

[0006] Moreover, since many patients already are intubated with centralvenous catheters for other clinically approved purposes anyway,providing a central venous catheter that can also cool the blood, ifonly to manage temperature and thereby ameliorate fever spikes, requiresno additional surgical procedures for those patients. A cooling centralvenous catheter is disclosed in the present assignee's co-pending U.S.patent application Ser. No. 09/253,109, filed Feb. 19, 1999 andincorporated herein by reference. The present invention is directed tosuch a device.

SUMMARY OF THE INVENTION

[0007] A heat exchange catheter, preferably made of urethane, includes acatheter body defining at least a coolant supply lumen and a coolantreturn lumen. First and second heat exchange membranes are disposedalong a distal portion of the catheter body, and the heat exchangemembranes communicate with one or more of the lumens. With thisstructure, coolant can be supplied to the heat exchange membranes viathe coolant supply lumen and received from the heat exchange membranesvia the coolant return lumen to effect a closed loop heat exchanger forcooling and/or warming a patient.

[0008] Preferably, the first and second heat exchange membranes definefirst and second interiors respectively communicating with first andsecond coolant supply ports in the coolant supply lumen. Also, first andsecond coolant return ports are formed in the coolant return lumen, andcoolant flows from the heat exchange membranes through the return ports.At least one anchor can be engaged with the catheter body to fasten thecatheter to a patient.

[0009] In addition to the coolant supply and return lumens, the cathetercan define a drug delivery lumen and a guide wire lumen. A connectormanifold can be engaged with the catheter body to interconnect thelumens with respective connector lines. More specifically, the connectormanifold defines plural channels, and each channel establishes arespective pathway for fluid communication between a respectiveconnector line and a respective lumen. As set forth in detail below, theanchor is on the connector manifold.

[0010] To provide for infusing medicament into a patient whilesimultaneously cooling the patient, at least one drug delivery port isformed in the catheter body. Preferably, the drug delivery port isformed at a location that is between two adjacent heat exchangemembranes to establish a pathway for fluid communication from the drugdelivery lumen to a location outside the catheter body. If desired,additional drug delivery ports can be formed along the length of thecatheter.

[0011] In another aspect, a method for making a heat exchange catheterincludes disposing a multi-lumen catheter body in a connector manifoldmold, and disposing plural connector tubes in the connector manifoldmold. Also, the method includes interconnecting a respective lumen witha respective connector tube using a mandrel, and then directing aplastic material into the connector manifold mold. The mandrels are thenremoved, such that a respective channel is defined between eachrespective lumen and its connector line.

[0012] In another aspect, a method is disclosed for treating a patient.The method includes advancing a heat exchange catheter device into thepatient, and then circulating coolant through the catheter device whilepreventing infusion of the coolant directly into the patient'sbloodstream. Per the present invention, the catheter device includes aheat exchange region that is established by: one or more heat exchangemembranes, or one or more hollow fibers, or one or more chamber-definingenclosures.

[0013] In still another aspect, a catheter configured as a Swan-Ganzcatheter or central venous catheter has at least one balloon-likemembrane distally located on the catheter for heating or cooling bloodin a patient. More particularly, the membrane defines an interiorcommunicating with a coolant supply lumen of the catheter and with acoolant return lumen of the catheter, to circulate coolant through theinterior of the membrane.

[0014] The details of the present invention, both as to its structureand operation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view of the present cooling catheter,schematically showing a medicament source and coolant source in anexploded relationship with the catheter;

[0016]FIG. 2 is a cross-sectional view as seen along the line 2-2 inFIG. 1;

[0017]FIG. 3 is a cross-sectional view as seen along the line 3-3 inFIG. 1; and

[0018]FIG. 4 is a top view of the interior of the connector manifold, asseen along the line 4-4 in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] Referring initially to FIG. 1, a therapeutic catheter system,generally designated 10, is shown for establishing and maintaininghypothermia in a patient, or for attenuating a fever spike in a patientand then maintaining normal body temperature in the patient. Commencingthe description of the system 10 at the proximal end, as shown thesystem 10 includes a cooling source 12 that can be a water-bath systemor a TEC-based system such as either of the systems disclosed inco-pending U.S. patent application Ser. No. 09/220,897, filed Dec. 24,1998 and incorporated herein by reference, or U.S. patent applicationSer. No. 09/260,950, filed Mar. 2, 1999, also incorporated herein byreference. In any case, the coolant source provides coolant such assaline through a coolant supply line 14, and coolant is returned to thesource 12 via a coolant return line 16. A catheter, generally designated18, includes a source tube 20 terminating in a fitting such as a femaleluer fitting 22. Also, the catheter 18 has a return tube 24 terminatingin a fitting such a male luer fitting 26. The fittings 22, 26 can beselectively engaged with complementary fittings 28, 30 of the lines 14,16 to establish a closed circuit coolant path between the catheter 18and coolant source 12.

[0020] Additionally, the catheter 18 includes a guide wire and primaryinfusion tube 32 that terminates in a fitting such as a female luer 34.A guide wire 36 can be advanced through the tube 32 in accordance withcentral venous catheter placement principles, or medicament or otherfluid can be infused through the guide wire and primary infusion tube32. Moreover, a secondary infusion tube 38 with female luer fitting 40can be selectively engaged with a medicament source 42 for infusingfluid from the source 42 through the secondary tube 38.

[0021] As discussed further below, the tubes 20, 24, 32, 38 are held ina distally-tapered connector manifold 44. As also set forth furtherbelow, the connector manifold 44 establishes respective pathways forfluid communication between the tubes 20, 24, 32, 38 and respectivelumens in a catheter body 46.

[0022] A suture anchor 48 advantageously is formed on the connectormanifold 44 for suturing the catheter 18 to a patient in accordance withcentral venous catheter operating principles. In one intendedenvironment, the suture anchor 48 includes opposed ears 50 formed withrespective suture holes 52. Other equivalent anchor structure can beused to hold the catheter 18 onto the patient, however, includingsurgical tape. When the catheter is a so-called Swan-Ganz catheter,i.e., a catheter of the type disclosed in U.S. Pat. No. 3,995,623,incorporated herein by reference, the anchor 48 typically would not beprovided.

[0023] In cross-reference to FIGS. 1 and 2, the catheter body 46includes at least two lumens, and in the preferred embodiment thecatheter body 46 includes at least four lumens. More specifically, thecatheter body 46 defines a generally wedge- or triangular-shaped (in thetransverse cross-section shown) coolant supply lumen 54, a generallywedge-shaped coolant return lumen 56, a round guide wire lumen 58, and awedge-shaped secondary infusion lumen 60. As mentioned above, however,the catheter can be a Swan-Ganz catheter, in which case additionallumens can be provided for Swan-Ganz catheter applications, including alumen for inflating an anchoring balloon for holding the distal tip ofthe catheter in an appropriate blood vessel for various heart-relatedmeasurements and another lumen for holding a wire or wires that areattached to one or more distally-located sensors, such as temperaturesensors, pressure sensors, gas sensors, and electrical sensors.

[0024] In any case, the connector manifold 44 establishes a pathway forfluid communication between the coolant supply tube 20 and the coolantsupply lumen 54. Likewise, the connector manifold 44 establishes apathway for fluid communication between the coolant return tube 24 andthe coolant return lumen 56. Further, the connector manifold 44establishes a pathway for fluid communication between the guide wire andprimary infusion tube 32, and the guide wire lumen 58, which terminatesat an open distal hole 62 defined by a distally tapered and chamfereddistal tip 63 of the catheter body 46. Also, the connector manifold 44establishes a pathway for fluid communication between the secondaryinfusion tube 38 and the secondary infusion lumen 60, which terminatesat an infusion port 64 in a distal segment of the catheter body 46.Additional ports can be provided for each lumen 58, 60 along the lengthof the catheter.

[0025] Referring now to FIGS. 1 and 3, at least proximal and distalthin-walled heat exchange membranes 66, 68 are arranged along the lastfifteen or so centimeters of the catheter body 46 and are bonded to theouter surface of the catheter body 46, with the infusion port 64 beinglocated between the heat exchange membranes 66, 68. Thus, each heatexchange membrane is about six centimeters to seven and one-halfcentimeters in length, with the heat exchange membranes beinglongitudinally spaced from each other along the catheter body 46 in thepreferred embodiment shown. Essentially, the heat exchange membranes 66,68 extend along most or all of that portion of the catheter 46 that isintubated within the patient. The heat exchange membranes can beestablished by a medical balloon material.

[0026] The heat exchange membranes 66, 68 can be inflated with coolantfrom the coolant source 12 as supplied from the coolant supply lumen 54,and coolant from the heat exchange membranes 66, 68 is returned via thecoolant return lumen 56 to the coolant source 12. In their inflatedconfigurations, the heat exchange membranes define a diameter of aboutten French, and preferably no more than twelve French. Thus, the heatexchange membranes 66, 68 are relatively long and comparatively thin, toadvantageously avoid excessively blocking blood flow through the venacava while nevertheless effecting patient cooling.

[0027] As shown in FIG. 3, a wall 70 separates the coolant supply andreturn lumens 54, 56. Taking the proximal heat exchange membrane 66 asan example, a supply port 72 is formed in the catheter body 46 throughwhich coolant from the supply lumen 54 can flow into the interior 74 ofthe heat exchange membrane 66, as indicated by the arrows 76. Moreover,a return port 78 is formed in the catheter body 46, and coolant can flowout of the heat exchange membrane 66 through the return port 78 and intothe return lumen 56, as indicated by the arrows 80. As can beappreciated in reference to FIG. 3, for each heat exchange membrane 66,68, the respective coolant supply port is distal to the respectivecoolant return port, to optimize fluid flow and heat transfer, althoughif desired the direction of fluid flow can be in the opposite direction.Both the coolant supply and coolant return lumens 54, 56 terminateproximal to the distal tip 63. For example, the coolant return lumen 56can terminate just distal of the coolant return port for the distal heatexchange membrane 68, and the coolant supply lumen can terminate justdistal of the coolant supply port of the distal heat exchange membrane68.

[0028] In any case, it may now be appreciated that coolant is circulatedthrough the catheter device 18 in a closed loop. That is, infusion ofthe coolant directly into the patient's bloodstream is prevented. Asdetailed above, the catheter device includes a heat exchange regionestablished by one or more heat exchange membranes. Alternatively, theheat exchange region can be established by or one or more hollow fibers,or one or more chamber-defining enclosures, such as metal or plasticbellows-type enclosures.

[0029] In the preferred embodiment, the components of the catheter 18are made of urethane, and more preferably are made of an aromatic,polyether-based polyurethane, although other suitable materials can beused. In a specific embodiment, the tubes 20, 24, 32, 38 are made ofTecothane TT-1095A made by Thermedics, Inc. of Woburn, Mass. Also, theheat exchange membranes 66, 68 are made of Pellethane 2363-65D, made byDow Chemical Corp. In contrast, the catheter body 46 is made ofTecothane TT-2055D-B20 with Barium Sulfate radiopacifying agentincorporated into the polymer matrix for optimum visualizing duringfluoroscopic maneuvering to a desired location. The catheter 18 can becoated with an anti-microbial agent and an anti-clotting agent ifdesired.

[0030] Now referring to FIG. 4, the details of the connector manifold 44can be seen. As shown, the preferred connector manifold 44 is flat andwedge-shaped, with the distal end 82 of the connector manifold 44 beingnarrower than the proximal end 84. Within the connector manifold 44,plural channels 86 are established. As can be appreciated in referenceto FIG. 4, each channel 86 establishes a respective pathway for fluidcommunication between a respective connector line 20, 24, 32, 38 and arespective lumen 54, 56, 58, 60. Owing to the wedge shape of theconnector manifold 44, the tubes 20, 24, 32, 38 are closely juxtaposedto each other near the distal end 82 of the connector manifold 44.

[0031] In making the connector manifold 44, the tubes 20, 24, 32, 38 arepositioned on what will become the interior of the connector manifold,and the catheter body 46 likewise is positioned on the connectormanifold, closely spaced from the distal ends of the tubes. A respectivemandrel is then advanced into each tube and the lumen of the catheterbody 46 that is to communicate with the tube. Next, plastic is directedover and around the tubes, mandrels, and catheter body 46 by insertmolding. The mandrels are removed after the plastic hardens,establishing the channels 86.

[0032] As envisioned by the present invention, the structure set forthabove can be used in many medical applications to cool a patient and/orto maintain temperature in a normothermic or hypothermic patient, forpurposes of improving the medical outcomes of patients on whom, e.g.,aneurysm surgery is to be performed, preferably while the patient'stemperature is below normal body temperature. The structure can then beused to rewarm the patient in a controlled manner by circulating warmcoolant through the structure, or by otherwise regulating natural bodyrewarming by circulating coolant that is maintained at an appropriatecool (relative to normal body temperature) or warm (relative to normalbody temperature) temperature through the structure.

[0033] As another example, head trauma can be treated by and afterlowering and maintaining the patient's temperature below normal bodytemperature. Or, cardiac arrest can be treated while the patient'stemperature is below normal body temperature. Yet again, minimallyinvasive heart surgery can be performed on the patient while thepatient's temperature is below normal body temperature. And, cardiacarrest in the patient can be treated by and while the patient'stemperature is below normal body temperature. Also, the presentinvention understands that for certain patients, e.g., stroke victims,it is important to maintain the temperature of a patient at or belownormal body temperature, when the patient runs or attempts to run afever. For severe ischemic stroke victims, the malady can be treated bymaintaining the patient's body temperature at a hypothermic level.

[0034] If desired, a temperature sensor 100 such as a thermistor orother suitable device can be attached to the catheter 18 as shown. Thesensor 100 can be mounted on the catheter 18 by solvent bonding at apoint that is proximal to the membranes 66, 68. Or, the sensor 100 canbe disposed in a lumen of the catheter 18, or attached to a wire that isdisposed in a lumen of the catheter 18, with the sensor hanging outsidethe catheter 18. Alternatively, a separate temperature probe can beused, such as the esophageal probe disclosed in co-pending U.S. patentapplication Ser. No. 09/282,971, filed Mar. 31, 1999 and incorporatedherein by reference. As yet another alternative, a rectal probe ortympanic temperature sensor can be used. In any case, the sensor iselectrically connected to the coolant source 12 for control of thetemperature of the coolant as described in the above-referenced '897 and'940 applications. While the particular CENTRAL VENOUS CATHETER WITHHEAT EXCHANGE MEMBRANE as herein shown and described in detail is fullycapable of attaining the above-described objects of the invention, it isto be understood that it is the presently preferred embodiment of thepresent invention and is thus representative of the subject matter whichis broadly contemplated by the present invention, that the scope of thepresent invention fully encompasses other embodiments which may becomeobvious to those skilled in the art, and that the scope of the presentinvention is accordingly to be limited by nothing other than theappended claims, in which reference to an element in the singular is notintended to mean “one and only one” unless explicitly so stated, butrather “one or more”. All structural and functional equivalents to theelements of the above-described preferred

What is claimed is:
 1. A heat exchange catheter, comprising: a catheterbody defining at least a coolant supply lumen and a coolant returnlumen; at least first and second heat exchange membranes disposed alonga distal portion of the catheter body and communicating with one or moreof the lumens, such that coolant can be supplied to the heat exchangemembranes via the coolant supply lumen and received from the heatexchange membranes via the coolant return lumen to effect a closed loopheat exchanger for cooling and/or warming a patient.
 2. The catheter ofclaim 1, wherein the first and second heat exchange membranes definefirst and second interiors respectively communicating with at leastfirst and second coolant supply ports in the coolant supply lumen and atleast first and second coolant return ports in the coolant return lumen.3. The catheter of claim 2, wherein the catheter is made of a urethane.4. The catheter of claim 1, further comprising at least one anchorengaged with the catheter body.
 5. The catheter of claim 1 wherein thecatheter defines at least a drug delivery lumen.
 6. The catheter ofclaim 5, wherein the catheter defines at least a guide wire lumen. 7.The catheter of claim 6, further comprising a connector manifold engagedwith the catheter body and interconnecting the lumens with respectiveconnector lines.
 8. The catheter of claim 7, wherein the anchor is onthe connector manifold.
 9. The catheter of claim 8, wherein theconnector manifold defines plural channels, each channel establishing arespective pathway for fluid communication between a respectiveconnector line and a respective lumen.
 10. The catheter of claim 9,wherein at least one drug delivery port is formed in the catheter bodyat a location that is between two adjacent heat exchange membranes toestablish a pathway for fluid communication from the drug delivery lumento a location outside the catheter body.
 11. A method for making a heatexchange catheter device, comprising the acts of: disposing amulti-lumen catheter body in a connector manifold mold; disposing pluralconnector tubes in the connector manifold mold; interconnecting arespective lumen with a respective connector tube using a mandrel;directing a plastic material into the connector manifold mold; andremoving the mandrels such that a respective channel is defined betweeneach respective lumen and its connector tube.
 12. The method of claim11, further comprising the act of engaging at least one heat exchangemembrane with a distal segment of the catheter body.
 13. The method ofclaim 12, wherein the catheter body is made of urethane.
 14. A methodfor treating a patient, comprising the acts of: advancing a heatexchange catheter device into the patient; and circulating coolantthrough the catheter device while preventing infusion of the coolantdirectly into the patient's bloodstream, the catheter device including aheat exchange region established by: one or more heat exchangemembranes, or one or more hollow fibers, or one or more chamber-definingenclosures.
 16. The method of claim 15, further comprising the act ofperforming aneurysm surgery while the patient's temperature is belownormal body temperature.
 17. The method of claim 15, further comprisingthe act of treating head trauma in the patient while the patient'stemperature is below normal body temperature.
 18. The method of claim15, further comprising the act of treating cardiac arrest in the patientwhile the patient's temperature is below normal body temperature. 19.The method of claim 15, further comprising the act of performingminimally invasive heart surgery on the patient while the patient'stemperature is below normal body temperature.
 20. The method of claim15, further comprising the act of treating cardiac malady in the patientwhile the patient's temperature-is below normal body temperature. 21.The method of claim 15, further comprising the act of maintaining thetemperature of a patient at or below normal body temperature, when thepatient runs or attempts to run a fever.
 22. The method of claim 15,further comprising the act of treating ischemic stroke in the patientwhile the patient's temperature is below normal body temperature. 23.The catheter of claim 1, further comprising a temperature sensorattached to the catheter body.
 24. The catheter of claim 3, wherein theurethane is an aromatic urethane.
 25. A catheter configured as aSwan-Ganz catheter or central venous catheter having at least onemembrane distally located on the catheter for heating or cooling bloodin a patient.
 26. The catheter of claim 25, wherein the membrane definesan interior communicating with a coolant supply lumen of the catheterand with a coolant return lumen of the catheter, to circulate coolantthrough the interior for heating or cooling a patient.